A multiphase power regulator (such as buck, boost, or buck-boost) employs multiple power stages, or phases, coupled in parallel to supply power to a bad (such as load current at a regulated voltage). Each power phase includes one or more power transistor/switches connected at a switch node to an inductor, with the parallel phases sharing input and output capacitors, and with a central controller for sequencing phase activation and providing phase duty cycle control. Multiphase regulators supply regulated power by selectively activating/inactivating the phases, with each active phase delivering load current based on a controlled switching duty cycle. Multiphase regulators can be designed for operation in discontinuous conduction mode (DCM) at light/medium loads that require lower load current (such that, during an active phase switching cycle, the phase operates in DCM), and/or for operation in continuous conduction mode (CCM) at medium/heavy loads that require higher load current (such that, during a phase switching cycle, each phase operates in CCM), including in some designs transitioning between DCM and CCM based on load current demand.